Hi,
I came across this repo while looking for the source for Traverso DAW. It's awesome, thank you!
To confirm, this is for open-source, cross platform media creation tools? I noticed some of those in the list are not cross platform but might be in the future, e.g. KWave.
With that in mind I think I've noticed some omissions:
Audio/DAWs:
Ardour - https://ardour.org/
LMMS - https://github.com/LMMS/lmms
Qtractor - https://www.qtractor.org/ - Unix only, however it uses Qt and JACK so it could be made to be cross platform.
Non DAW - https://github.com/falkTX/non/ - Again, Unix only at the moment, but because it uses FLTK and JACK it could be ported to cross platform. Seems to be rebooted using CMAKE (promising!) here: https://github.com/Stazed
Audio/Editors:
Jokosher - https://github.com/mjumbewu/jokosher
Sweep - https://github.com/kfish/sweep
Audio/Collections:
Most of these are Linux focused, but can be helpful for finding Open Source Cross Platform Apps.
https://linuxdaw.org/
https://linuxmusic.rocks/
https://wiki.linuxaudio.org/wiki/start
The Arch Wiki also has info regarding audio software: https://wiki.archlinux.org/title/List_of_applications/Multimedia#Audio
Powered by Faust has lots of cross-platform, open-source projects: https://faust.grame.fr/community/powered-by-faust/
Not strictly a resource but https://linuxmusicians.com/ can be helpful too.
Video/Editors:
Kdenlive - https://kdenlive.org/
Blender - https://www.blender.org/ (Has great video editing capabilities.)
Video/Tools:
OBS - https://obsproject.com/
If any/all of these are inappropriate please feel free to disregard. Thanks again!